Fully automatic keyway shaper



y 0, 1966 J. R. BASHQR 3,250,181

FULLY AUTOMATIC KEYWAY SHAPER Original Filed Nov. 19, 1962 9Sheets-Sheet l INVENTOR. JAMES R BA 5H0 ATTORNEY J. R. BASHOR May 10,1966 FULLY AUTOMATIC KEYWAY SHAPER 9 Sheets-Sheet 2 Original Filed Nov.

INVENTOR.

JA MES R. 8/3 SHOE 5 ATTO NEY May 10, 1966 J. R. BASHOR FULLY AUTOMATICKEYWAY SHAPER 9 Sheets-Sheet 5 Original Filed Nov. 19 1962 Killlllll INVENTOR.

JAMES R. BASHOR ATTORNEY J. R. BASHOR FULLY AUTOMATIC KEYWAY SHAPER May10, 1966 9 Sheets-Sheet 4 Original Filed NOV. 19 1962 INVENTOR. JAMES RBASHOR AT ORN May 10, 1966 J. R. BASHOR FULLY AUTOMATIC KEYWAY SHAPER 9Sheets-Sheet 5 Original Filed Nov. 19

ATTORNEY y 10, 1966 J. R. BASHOR 3,250,181

I FULLY AUTOMATIC KEYWAY SHAPER Original Filed Nov. 19, 1962 9Sheets-Sheet 6 11 ll ll;ll\ llllLU] Hfllll llll HI] INVENTOR. JAMES R-BASHOR ATTORNEY May 10, 1966 Original Filed Nov. 19 1962 J. R. BASHORFULLY AUTOMATIC KEYWAY SHAPER 9 Sheets-Sheet '7 INVENTOR.

JAMES R. BASHOR 2: 9- BY ATTORN May 10, 1966 J. R. BASHOR 3,250,181

FULLY AUTOMATIC KEYWAY SHAPER Original Filed Nov. 1, 1962 9 Sheets-Sheet8 45 INVENTOR. JAMES R BASHOR BY I .18 X/ ATTORNE 9 Sheets-Sheet 9 J. R.BASHOR FULLY AUTOMATIC KEYWAY SHAPER May 10, 1966 Original Filed Nov.19,

INVENTOR.

ATTO R N E JAMES R- BA 5710/? United States Patent I 3,250,181 FULLYAUTGMATIC KEYWAY SHAPER James R. Bashor, Cincinnati, Ohio, assignor toUnited States Drill Head Company, Cincinnati, Ohio, a corporation ofOhio Original application Nov. 19, 1962, Ser. No. 238,472, now PatentNo. 3,195,414, dated July 20, 1965. Divided and this application Feb.25, 1965, Ser. No. 457,885

Claims. (Cl. 90-24) This is a division of application Serial No.238,472, filed Nov. 19, 1962, now Patent No. 3,195,414, issued July 20,1965.

This invention relates to an internal keyway or slot cutter, such as maybe employed in cutting keyways or slots in blind or through holes of aworkpiece.

An object of the invention is to greatly facilitate and expedite thecutting of a slot or keyway within a bore of a workpiece.

Another object is to achieve unusual accuracy in slotting a wall of abore parallel to the bore axis.

3,250,181 Patented MaylO, 1966 FIG. 14 is a bottom plan view ofenlarged.

ice

the same, likewise FIGS. 15, 16 and 17, are respectively, side, top,and,

bottom views of a cutter, on a greatly enlarged scale, adapted to besupported by the cutter bar shown in FIGS. 10 and 11.

FIG. 18 is a vertical cross-section of the cutter support bar with acutter and an insert assembled therein, together with means forrotationally rocking the insert and feeding the cutter, and showing aworkpiece superposed thereon in readiness for internal slotting.

FIG. 19 is a view similar to FIG. 18, part being broken away, andshowing the workpiece at an intermediate stage of internal slotting.

FIG. is an enlarged cross-section taken on line 2020 of FIG. 18.

FIG. 21 is an enlarged cross-section taken on line 21-21 of FIG. 20, andshowing the workpiece slotted Way cutting operation. and the quality ofthe work performed, by automatically dislodging chips from the boreconcurrently with each withdrawal of the tool bar, this resulting alsoin prolonging the life of the cutting tool.

A further object is to provide high production apparatus for precisioncutting of keyways or slots in a workpiece bore.

means described herein and illustrated upon the accompanying drawings,in which:

FIG. 1 is a perspective view of the front of the machine embodying thepresent invention.

FIG. 2 is a fragmentary front elevation of a cam drive means and headactuating mechanism.

FIG. 3 is a side elevation of the structure illustrated byFIG. 2.

FIG. 4 is a fragmental detail view of the cam and head actuating means.

FIG. 5 is a cross-sectional view taken on line 55 of FIG. 3, showingpart of a cutter feed mechanism in initial starting position.

FIG. 6 is a view similar to FIG. 5, showing the cutter feed mechanismadvanced to a position of maximum cutter feed.

FIG. 7 is an enlarged cross-section taken on 7-7 of FIG. 5, andindicating by means of broken lines an elevated and a lowered positionof a head which carries the workpiece to be slotted.

FIG. 8 is a plan view of a cutter feed control cam, constituting adetail of the invention.

FIG. 9 is a side elevation of the same.

FIG. 10 is a side elevation of a cutter support bar embodying theinvention.

FIG. 11 is a cross-section taken on line 1111 of FIG. 10.

FIG. 12 is a side elevation of cutter bar insert, which is adapted torock axially within the cutter bar of FIG. 11.

FIG. 13 is atop plan view of the insert, on an enlarged scale.

The foregoing and other objects are attained by the to an intermediatedepth by the cutter.

FIG. 22 is a view similar to FIG. 21, but showing the cutter advanced tomaximum slot depth.

FIG. 23 is a perspective view of a typical and exemplary workpiecefinished by internal slotting in accordance with the present invention.

FIG. 24 is a view similar to FIG. 5, on smaller scale and part brokenaway, showing a modification by means for control of the cutter feed.

Common practice in the cutting of internal keyways longitudinally of aworkpiece bore, has been to rigidly clamp the workpiece upon astationary support, and reciprocate within the bore a cutter fixedlymounted upon a cutter'bar fed, both longitudinally and laterally withinthe bore for removal of metal at the keyway location. The bar carryingthe cutter was necessarily much smaller in diameter than the workpiecebore, and the end thereof opposite the cutter end was invariably mountedupon a feed carriage at a location outside the entrance end of theworkpiece bore.

By reason of the remoteness of the bar mount from the area of out withinthe bore, the bar was subject to slight bending which caused chatter asthe cutter performed to remove metal at the keyway, this resulting inrough machining and inaccurate keyway depth dimensions, aggravated inmany instances by a tendency of the cutter to wander sidewise of theline'of cutting due to twist or lateral bending of the cutter bar, or toplay resulting from wear inthebar feed mechanism. Thus, it was notuncommon for a completed keyway to be defective as to depth, finish,uniformity of width, or crookedness. Such defects were often found tointerfere with the rapid and accurate assembly of machined parts orcomponents.

Deficiencies such as those above mentioned, accounted for undue cutterwear and breakage, which interfered with rapid production schedules andcost estimates. Such considerations have been largely minimized by meansof the present invention.

With reference to the drawings, FIG. 23 illustrates a typical workpiecein the form of a high alloy steel spindle, whose internal keyway hasbeen cut accurately and smoothly using the means of the presentinvention. Under actual production conditions, the keyway was cut inthirty-five seconds, whereas by conventional method the production timerequired 8 to 10 minutes of machining.

It, is to be understood that the workpiece may difier considerably fromthe' disclosure of FIG. 23, which is merely exemplary. The workpiece mayas well be a gear, a pulley, or a metallic mass of any shape, havingeither a blind bore or a through bore to be slotted internally.

When the bore to be slotted is a blind bore, as FIG. 23 indicates, thewall 30* of workpiece 31 is preferably drilled transversely to provide arelief hole 32 at which the cutter ends its cutting stroke, so as toavoid its striking the bottom of bore 33. The machined keyway or slot isthroughout the drawings indicated by the character S, and the tool whichcuts the keyway or slot is designated the cutter C. The workpiece isdesignated W.

With reference to FIG. 1, it may be noted that the drawing depicts fourdifferent workpieces W, varying as to size or shape, and each being heldby clamps or chucks 34 carried by the movable head 35 of the machine.Head. 35 is adapted for vertical reciprocation by means of plungers 36to which the head is fixed at 37, the plungers being operative inunison.

At B are indicated cutter bars, held stationary in the course of aslot-cutting operation, and each carrying a cutter C. In operation, theworkpieces fixed to the head descend repeatedly about the cutter bars,the latter entering the bores of the workpieces with very closetolerance so as to have bearing support all around the wall of the bore.Thus, during every pass of the cutter, the bar carrying the cutter isbacked up by the wall of the bore to eliminate any tendency of thecutter bar to bend or twist while the cutter is removing metal from theworkpiece wall.

In the course of the slotting procedure, the sharpened tip of the cutteris progressively advanced laterally of the bar axis, for deepening theslot in stages until the desired depth is achieved. At the beginning ofthe slotting procedure, of course, the tip of the cutter is enshroudedwithin the limits of the bar, see FIG. 18. In FIG. 19, cutter C is shownadvanced laterally to about half of its advancement limit, wherefore ithas performed to cut about half of the required depth'of the slot orkeyway S.

The stages of cut just mentioned, are indicated likewise upon FIGS. 20and 21. The cutter limit of advancement is depicted in FIG. 22, whereinthe keyway or slot S is .at maximum depth and is completed. Thecharacters 38 indicate replaceable wear strips carried by the cutter barin the region of the cutter, for maintaining a close sliding fit of thecutter bar within the smooth bore of the workpiece while the cutter isremoving metal.

It may here be pointed out that the workpieces W shown in FIG. 1 may beidentical to one another if desired, and in that event the severalcutter bars operative thereon will also be identical to one another.Thus, 'a plurality of identical workpieces may be machined at one timefor increasing output. The number of workpiece stations may of course beincreased or decreased in number, to achieve a desired output rate.

The cutter bar B, FIGS. to 22, may comprise a,

turned hollow body having a conical upper end 40, and an enlarged lowerend carrying an annular flange or base 41 whereby the bar may bedetachably secured, as by means of an encircling nut 42, in fixedrelation to the machine housing 43. The housing may include a reinforcedupper bonnet or stationary support 44, carrying a series of mountingelements in the form of bored cylindrical sleeves 45 (FIG. 18), one foreach cutter bar, and fixedly mounted in any suitable manner upon thebonnet. Each sleeve may have an externally threaded upper end 46 toaccommodate the threads of a nut 42, whereby bar B may be detached, andreplaced by another whenever necessary.

At its upper end 40 (FIG. 11), the cutter bar is provided with atransverse through-passageway or socket 47, preferably rectangular incross-section, toreceive a bar of tool by FIGS. 15, 16, 17. The lengthof the cutter must not exceed the diameter of bar B at socket 47. Thisassures initial entry of the cutter into the workpieces bore withoutinterference by the cutter, in setting up the workpiece for clampingupon head 35. With the workpiece initially fitted over the cutter bar B,as in FIG. 18, the workpiece is ready for clamping to the head, and thisis accomplished preferably by means of pneumatic or hydraulic clamps,the jaws of which adjust to the position of the workpiece and hold itfirmly without shifting the workpiece. Such self-adjusting clampingdevices or chucks are readily available in the market.

As FIG. 11 shows, cutter socket 47 preferably is inclined slightly toneutralize any tendency of the cutter to gouge in view of the upturn ofcutter tip 48, FIG. 15.

It may here be noted that the bottom face 50 of the cutter C istransversely channeled or recessed at 51, with the sides 52 of thechannel slightly flared downwardly and outwardly, for a purpose to beexplained.

For feeding and withdrawing the cutter through socket 47, there isprovided the cutter bar insert of FIG. 12, which is insertable in thebore 53 of the cutter bar. The insert 54 is in etfect a turned shafthaving a lower end 55 enlarged in diameter and provided with a taperedcrossslot 56 adapted to receive a key or tongue for rockingly rotatingthe insert within the bore of bar B. The insert is to have a nice fitwithin the bar bore, and may be bushed as indicated at 57 of FIG. 18.

At its upper flat end 58 the insert is drilled longitudinally, and offcenter, to receive a pin 60 provided with a tapered head 61 that extendsbeyond the end 58 of the insert. The pin head 61 is eccentric to theaxis of the insert 54 (FIG. 13). The taper of the eccentric head 61 iscomplementary to the taper of cutter channel 51, so that when a cutteris placed in socket 47 of cutter bar B, and insert 54 is projectedupwardly into the bore of said bar, the eccentric head 61 will nicelyand without clearance repose within the cutter channel 51.

It will be evident from the foregoing explanation, that step rotation ofinsert 54 will cause the eccentric head 61 to advance cutter C stepwisealong the length of socket 47. One-half rotation of insert 54 will shiftthe cutter from the fully retracted or home position of FIG. 20, to thefully advanced position of FIG. 22. The travel of cutter C is tocorrespond with the depth of the keyway desired, and is dependent uponthe eccentricity provided for head 61.

Accordingly, if the workpiece is bodily recip-rocated relative to thecutter bar, and if insert 54 is slightly rotated each time the workpieceis lifted off the cutter bar, then with each advancement of theworkpiece onto the cutter bar a deeper cut will be performed by cutterC. Upon execution of a predetermined number of workpiece reciprocations,the cutter will have finally assumed a position of full advancement(FIG. 22), at which time the keyway will have been completed and theworkpiece will then be unclamped and removed from the machine.

The character 62 (FIG. 18) indicate-s a locating pin anchored in fixedsleeve 45 and adapted to register with a slot 63 in the base of cutterbar B, to assure a definite disposition of cutter C with respect to theworkpiece, so that all workpieces will be key-slotted at the .same location within the workpiece bore.

Step rotation of insert 54 and its eccentric 61, is effected through apinion 64 which is fixed upon the lower end of a hollow rock shaft 65journaled in bearin-gs 66 of sleeve 45. The bore 67 of the rock shaftcarries a stud 68 which, by means of a pin and slot connection 20, ispermitted limited longitudinal, shifting movement within the lbOfC, butis held against rotation therein. Stud 68 is constantly urged upwardlyby a spring 71.

Formed integrally with stud 68 is an upstanding key 72 taperedcomplementarily to cross-slot 56 of the insert 54, so that key 72 maydrive the insert without play or backlash occurring. The top of key 72may carry an upstanding locating pin 73 adapted to enter an offset hole74 in the base of insert 54, so that the key will properly register withcross-slot 56 whenever cutter bars are replaced or substituted. Pinion64 is adapted for step r0- tation in the course of the slottingoperation, as will be explained.

Referring to FIG. 5, the character 75 indicates a longitudinallyvshifta-ble cutter feed bar which is slidably supported in bearings 76carried by the machine housing. Bar 75 is constantly biased toward theleft by a suitable spring 77. The bar carries a cam follower 78, whichby the force-of spring 77, is yieldingly held in contact with a cutterfeed cam 80. Feed cam 80 is detailed in FIGS. 7, 8 and 9, and is seen tocomprise a flat disc having its perimeter provided with alternate humps81 a and depressions 82, over which travels the cam follower 78 as thecam is slowly rotated.

The perimeter of cam 80 is in general a volute, and has therefore a highpoint 84 and a low point 83. Thus,

.with reference to FIG. 5, if cam 80 is slowly rotated incounter-clockwise direction, the follower on bar 75 will beprogressively shifted to the right, carrying with it the feed bar 75until finally the bar reaches the position of maximum shift, asillustrated by FIG. 6.

Such shifting of feed bar 75 acts to rotate the rockers 85 about theirstationary pivots 86, from the FIG. 5 position to the FIG. 6 position,thereby causing the gear segments 87 of the rockers to rotate eachpinion 64 through 180 degrees. As was previously explained, this amountof pinion movement results in advance of cutter C from the fullyretracted position of FIG. to the fully extended position of FIG. 22. Ascam 80 continues to rotate (FIG. '6), the high point 84 of the cam willmove past the follower 78, whereupon the latter will descend to'the lowpoint 83 of the cam (see FIG. 5), for returning the rockers and pinions64 to the initial or home position of FIG. 5. At the home position,cutters C will be fully retracted, as previously explained.

In connection with the foregoing explanation, it must be appreciatedthat the feed of a cutter C is advanced slightly each time that theworkpiece is withdrawn fully from the cutterbar, so that a deeper cut isperformed with every pass of the workpiece over the cutter. Also,whenever the cutter completes a pass within the workpiece bore, thecutter is relieved by slightly reversing its feed at approximately thesame time that the work- In consequence, the follower 78 beginning atthe low 1 point of the cam, travels, onto the first hump '81, whereuponthe follower and bar 75 are shifted longitudinally to slightly actuate arocker85 which in turn slightly rotates a pinion 64, thereby to extendthe cutter in readiness for a first keyway cut. By the time the firstcut is completed, the cam has moved to bring the follower to thedepression 82 following the first hump, which results in a rockermovement that reverses the rotation of pinion 64 and thereby effects aslight retraction of cutter C for relieving the latter as the workpiecebegins to recede off the cutter bar. Thus, the cutter is prevented fromscraping the metal during the receding stroke of the workpiece.

The next cut is set up by the follower mounting the second hump 81 ofthe rotating cam. The second hump, being slightly farther from the camcenter than is the first hump, feeds the cutter C a greater distance inreadiness for the second keyway cut, and this occurs while the workpieceW is withdrawn, as shown in full lines at the top of FIG. 7. Thus, ascam 80 continuously rotates with its driven palette 90, the cutter C(one or more) is alternately fed and relieved to progressively form thekeyway, until finally, upon completion of a full rotation of cam 80, thefollower 78 drops off the high point of the cam and returns to startingposition at the low point 83. At the same time, the machine is stoppedto permit removal of the finished workpiece, or workdeclutching it.

Referring back to FIGS. 2 to 7, the characters 92 indi-- cate suitablepivots between one end of each rocker and a cooperative pivot block 93fixed upon the feed bar 75. The details of this pivot connection areunimportant to the present invention.

The modification of FIG. 24 illustrates a simplified form of means fortranslating reciprocatory movements of feed bar 75 to the several cutterfeed pinions 64. Here the rockers 85, their pivotal mountings, and theblocks 93 are eliminated, and in place thereof are installed simpletoothed racks 94 fixed upon the feed bar 75 with their teeth meshingwith the pinion teeth. In this construction, feed bar 75 may be squarein cross-section where the racks are applied, and may in fact be squarethroughout its length so as to slide in square journals at 76 to assurenon-rotation of the bar while permitting longitudinal shifting under theinfluence of follower 78 and spring 77 or its equivalent.

It may be noted from several of the drawing views that cutter feed cam80 overlies a second cutter feed cam, identified as 180, which latter issimply an alternative whose peripheral contour may incorporate certainjusted rotationally relative to the palette, at screws 95,

FIG. 8.

The main drive for the apparatus is best illustrated by FIGS. 2, 3 and4, and includes the electric motor 91 Whose shaft drives the input shaft96 of a reduction gear I box 97. The output shaft 98 of the gear boxmaycarry a sprocket 99 driving a chain 100, which in turn drives thesprocket 101 and shaft 102 of a second gear box 103 that supports therotational stud 104 of palette 90. The speed reduction desired may beobtained with the use of suitable worms 105, 106, and cooperative wheelsas shown in FIG. 4. This may constitute the drive for the cutter feedcam 80, or 180.

Fixed to the output shaft 98 of gear box 97, are two cranks 107 and 108(FIG. 2), which rotate with said shaft. The outer or swinging ends ofthe cranks have pivotal connection at 109 with the lower ends of links110. The upper ends of the links at 112 have pivotal connections withcollars 113, which collars are fixed to the vertically reciprocableplungers 36 that carry the work head 35 at their upper ends, FIG. 1. Theplungers slide in suitable fixed journals 114 and 115 carried by themachine housing.

From the foregoing, it will be apparent that rotation of the motor andshaft 98 will reciprocate the plungers 36 and the work head attachedthereto, between limits indicated upon FIG. 2 by full lines 113 andbroken lines 116, which corresponds to the throw of cranks 107 and 108.The crank throw is to exceed, at least slightly, the length of a keywayto be formed in a workpiece attached to head 35.

The gearing above described shall be such as to feed the cutter C inincrements as determined by-the humps 81 of feed cam 80, and the numberof head reciprocations being equal to the number of humps traversed byfollower 78 as the cam rotates a full turn. By the time the cam moves afull turn, the cutter will have executed its final pass to complete thekeyway, and will be restored to starting position for a subsequent cycleof operation. By means of a simple electric switch arrangement, notshown, the circuit of motor 91 may be opened after the final cut of thetool, or upon a complete rotation of cam 80, to permit removal of thefinished workpiece and application of another to be machined.

In FIG. 1, 117 indicates an electric control panel including a group ofswitch buttons 118 and other devices providing for starting, jogging,emergency stopping, and other controls which may be considereddesirable. Such other controls may include means to initiate powerclamping and release of the workpieces, which are not necessarilydetailed in the present disclosure. The machine may include alsoautomatic means for lubrication of parts, and for supplying coolant tothe cutters and workpiece bores. In this connection, it is pointed outthat suitable quickly-detachable coolant supply nozzles 119, FIG. 7, maybe arranged to inject coolant fluid constantly into the relief holes 32of the workpiece bores, to flush chips from the bores as the workpieceswithdraw repeatedly from the cutter bars in the course of machining.

It is noteworthy that during the entire keyway cutting operation, thebore of the workpiece is vertical and open downwardly, so that chipsfrom the cutting operation drop by gravity and/ or flushing betweensuccessive cuts made by the tool or cutter. It is therefore impossiblefor chips to accumulate at the blind end of the bore, and thereby causecutter damage or breakage as the cutter approaches the end of its inwardtravel limit. This is an important feature of the structure.

The bonnet 44 of the machine housing by preference is dished to providea cavity 120, to catch coolant fluid and return it to a sump within thehousing, whence it is recirculated by pump action to the cutting area.Also, in a modification of head 35, the top surface thereof may beplaned flat and slotted in much the same manner as a shaper table, foraffixation of workpieces by means of conventional clamps and bolts.

It is to be understood that various other modifications and changes maybe made in the structural details of the apparatus, within the scope ofthe appended claims, without departing from the spirit of the invention.

What is claimed is:

1. An internal keyway or slot cutting machine, comprising incombination, a stationary support, and a head reciprocable toward andfrom the support, means on the head for securing a bored workpiece, withthe bore open toward the support, a cutter bar fixed in upstanding position upon the stationary support, and including a cutter feedablelaterally of said bar from a retracted position within the confines ofthe bar, to a position of extension beyond the bar limits, said cutterbar with the cutter retracted being dimensioned to have a bearing fitwithin the workpiece bore, for backing up the cutter when extended tocutting position, means operative to intermittently extend the cutterfor progressive removal'of metal from the workpiece bore, and means forreciprocating the head to repeatedly drive the workpiece toward thecutter bar, with the bar centered in the bore.

2. The apparatus as set forth in claim 1, wherein the combinationincludes means for terminating reciprocatory movements of the head,substantially concurrently with disposition of the cutter to fullyextended position.

3. An internal keyway or slot cutting machine, comprising incombination, a stationary support, and a head reciprocable toward andfrom the support in a substantially vertical plane, means on the headfor securing a bored workpiece, with the bore upstanding and open in thedirection of the support, a cutter bar upstanding upon the stationarysupport, and including a cutter feedable laterally of said bar from aretracted position within the confines of the bar, to a position ofextension beyond the bar limits, said cutter bar with the cutterretracted being dimensioned to have a bearing fit within the bore, forbacking up the cutter when extended to cutting position, means forreciprocating the head to lower the workpiece bore about the cutter barand to raise it therefrom repeatedly, and means operative in advance ofeach head lowering movement, for laterally extending the cutter toremove metal from the wall of the bore, the head in raising serving toclear the cutter bar for gravitation of chips from the bore after eachcut.

4. The apparatus as set forth in claim 3, wherein the alignment with thestationary cutter bar, means for reciprocating the head to lower theworkpiece bore about the cutter bar and to raiseit therefrom repeatedly,and means operative in advance of each lowering movement of the head,for laterally extending the cutter to remove metal from the wall of theworkpiece bore, the head in raising serving to clear the cutter bar forgravitation of chips from thebore after each cut.

6. The apparatus as set forth in claim 5, wherein the combinationincludes means for injecting fluid under pressure into the bore, toassist gravitational flow of chips from the lower open end of theworkpiece bore.

7. An internal keyway or slot cutting machine, comprising incombination, a stationary support, and a head reciprocable bodily towardand from the support, means on the head for securing a bored workpiece,with the bore open toward the support, a longitudinally bored cutter barhaving a base, and means fixing said base upon the stationary supportwith the cutter bar aligned axially with the bore of the workpiece, saidcutter bar having an upper end transversely channeled, and dimensionedto have a bearing fit within the workpiece bore whereby the workpiece issnugly slidable over the cutter bar as the head aforesaid isreciprocated, a cutter of lesser length than the diameter of the upperend of the cutter bar, said cutter having a sharpened tip normallyhoused within the transverse-channel, and a body portion having a recesstherein, the body portion of the cutter being longitudinally slidable inthe cutter bar channel for selective projection of the tip from a fullyretracted position within the confines of the channel, to an extendedposition laterally outside the channel, a rock shaft rotationallysupported within the longitudinal bore of the cutter bar, said shafthaving an eccentric end fitted to the recess of the cutter, fortranslating axial rocking movements of the shaft to longitudinalmovements of the cutter within the cutter bar channel, means for bodilyreciprocating the head carrying the workpiece, and rotary cam means forstep-rotating the rock shaft to partially extend the cutter by action ofthe eccentric upon each disposition of the head to one of its limits oftravel, and to reversely rotate the rock shaft between successivecutter-extending step-rotations, upon disposition'of the head to itsopposite limit of travel, the reverse rotations of the rock shaft beingof lesser extent than the preceding cutter-extending step-rotation.

8. The apparatus as set forth in claim 7, wherein the rotary cam meansincludes means operative after a predetermined number ofcutter-extending step rotations of the rock shaft, to return the cutterto fully retracted position within the channel of the cutter bar.

9. An internal keyway or slot cutting machine, comprising incombination, a stationary support, and a head reciprocable bodily towardand from the support, means on the head for securing a bored workpiece,with the bore open toward the support, a longitudinally bored cutter barhaving a base fixed upon the stationary support with the cutter baraligned axially with the workpiece bore, said cutter bar having an upperend transversely channeled, and dimensioned to have a bearing fit withinthe workpiece bore whereby the workpiece is snugly slidable over thecutter bar as the head aforesaid 1s reciprocated, an elongate cutter nogreater in length than the distance across the upper end of the cutterbar, said cutter having a sharpened tip normally disposed within thelimits of the channel, and a body portion longitudinally slidable in thechannel for selective pro jection of the tip outside the channel to acutting position, a rock shaft rotationally supported within thelongitudinal 'bore of the cutter bar, and cooperative means on thecutter and said rock shaft for translating axial rocking movements ofthe shaft to longitudinal movements of the cutter, means for bodilyreciprocating the head carrying the workpiece, and cam means forsteprotating the rock shaft to' partially and progressively extend thecutter upon each disposition of the head to one of its limits of travel,and to reversely rotate the rock shaft partially, between successivecutter-extending step-rotations, upon disposition of the head to itsopposite limit of travel, the reverse rotations of the rock shaft beingof lesser extent than the preceding cutter-.

extending step-rotation.

10. The apparatus as set forth in claim 9, wherein the cutter bar andthe workpiece bore are disposed in an upright position, with an end ofthe workpiece bore opening downwardly, to release cutter chips bygravity upon each movement of the workpiece off the upper end of thecutter bar.

WILLIAM W. DYER, JR., Primaly Examiner.

1. AN INTERNAL KEYWAY OR SLOT CUTTING MACHINE, COMPRISING INCOMBINATION, A STATIONARY SUPPORT, AND A HEAD RECIPROCABLE TOWARD ANDFROM THE SUPPORT, MEANS ON THE HEAD FOR SECURING A BOARD WORKPIECE, WITHTHE BORE OPEN TOWARD THE SUPPORT, A CUTTER BAR FIXED IN UPSTANDINGPOSITION UPON THE STATIONARY SUPPORT, AND INCLUDING A CUTTER FEEDABLELATERALLY OF SAID BAR FROM A RETRACTED POSITION WITHIN THE CONFINES OFTHE BAR, TO A POSITION OF EXTENSION BEYOND THE BAR LIMITS, SAID CUTTERBAR WITH THE CUTTER RETRACTED BEING DIMENSIONED TO HAVE A BEARING FITWITHIN THE WORKPIECE BORE, FOR BACKING UP THE CUTTER WHEN EXTENDED TOCUTTING POSITION, MEANS OPERATIVE TO INTERMITTENTLY EXTEND THE CUTTERFOR PROGRESSIVE REMOVAL OF METAL FROM THE